Study On Gas Sensor Based On CuO/In₂O₃ Materials

Nowadays,with the rapid development of science and technology and the rapid progress of global industrialization,the environmental pollution on Earth is getting more and more serious,alongside the overuse of natural resources.Every single second in our daily life,a large amount of flammable,explosive and toxic gases,such as carbon dioxide,nitrogen oxides,hydrogen,SOx,methane and so on,are discharged into the atmosphere.Therefore,the research of gas sensors plays a vital role these years.Gas sensors are divided into a number of different types like electric chemical formula,contact combustion type and semiconductor type optical type,etc.Semiconductor metal oxide gas sensors,which possess high sensing performance with high sensitivity and low manufacturing cost,are widely used in various fields because they are suitable for mass production.There are many kinds of synthesis methods of semiconductor metal oxide,such as sol-gel method,HEMM,hydrothermal synthesis method,chemical precipitation method and so on,which are commonly used at home and aboard.Microemulsion method is a new method for the synthesis of nanomaterials.Compared with the common synthesis methods mentioned above,it has the advantages of size controllingand easy configuration.The composition is also of high dispersity.As typical n-type and p-type semiconductor metal oxides,In₂O₃ and Cu O have shown a perfect prospect in the field of optoelectronics as well as the research field of gas sensors.Firstly,we respectively synthesis In₂O₃ and Cu O materials by microemulsion method and microwave hydrothermal method,with XRD and SEM used to observe the structure and morphology of the material after that.By comparing the gas-sensing properties of the materials synthesized by two methods,it is found that the nano-particles synthesized by the microemulsion method exhibit small size effect,which is beneficial to the interaction between target gas and materials.Secondly,In₂O₃ and Cu O nano-particles which prepared by microemulsion method were compounded by physical doping to test the gas sensitivity of Cu O/In₂O₃composites with different composite ratios.The results of the test showed that the doping of Cu O not only reduced the working temperature of the material to gas reaction,but also had a larger detection range and better selectivity.XPS analysis showed that the doping of Cu O increased the oxygen vacancy concentration,and electron transfer were found between the two materials.After that,the Cu O/In₂O₃ composites with different composite ratios were synthesized by one-step microemulsion method.Compared with indium oxide alone,the constructed gas sensor of the composites has higher sensitivity,larger detection range,better selectivity and shorter response/recovery time.Finally,the effects of one-step microemulsion method and physical doped Cu O/In₂O₃ materials on the gas sensitivity of NO₂ were compared.Basing on this we explainedthe reason why Cu O/In₂O₃ composite material prepared by one-step microemulsion method has better gas sensitivity to NO₂.